As Gov. John Hickenlooper signed a new civil unions law today, activists know it represents a victory long fought for by LGBT Coloradans.

The state is the source of a case that produced a landmark decision for LGBT equality from the U.S. Supreme Court. In 1996 justices ruled 6-3 in a case called Romer v. Evans to strike down Colorado's voter-approved Amendment 2 as unconstitutional. The amendment barred the state or any governmental unit within it from enacting laws prohibiting sexual orientation–based discrimination.

Justice Anthony Kennedy, who activists are now counting on as a swing vote when the high court considers marriage equality starting next week, wrote the majority opinion. As a result, since 2007, Colorado has outlawed discrimination against anyone based on sexual orientation or gender identity.

Meanwhile, in 2006, Coloradans voted to constitutionally ban same-sex marriage by limiting marriage to "only between one man and one woman." Voters also made it clear they wouldn't recognize same-sex marriages performed in other states.

This year marks the third try for civil unions instead. The most recent failure, in 2011, ended in a procedural move by Republicans that shut down the legislature on the last day of the session, ensuring the bill couldn't be voted on despite having the votes to pass.

But with the latest election, Coloradans sent Democrats into power in both the Senate and House. In the Senate, gay Democrat Pat Steadman, whose partner died in September, had long been fighting for equality. He introduced the civil unions legislation and it passed 21-14 on February 12. The House — which had selected a gay man, Mark Ferrandino, as its speaker — voted 39-26 for the legislation March 12.

With the addition of Hickenlooper's signature today, the new law goes into effect in Colorado on May 1.

The Roman Catholic Church has threatened to leave the adoption business over civil unions, arguing that as a state contractor it would be forced to recognize the unions and claiming that is incompatible with Catholic faith. Catholic Charities had already made the same move in Illinois after civil unions become law there.